Godfrey Hounsfield and the dawn of computed tomography.

OBJECTIVE: To provide a historical account of the events surrounding the development of the computed tomography scanner. METHODS: Information was obtained by interviewing people who worked with Sir Godfrey Hounsfield and Dr. James Ambrose at Atkinson Morley's Hospital in the 1970s, and from published books, articles, and several web sites, including the Nobel web site. RESULTS: The computed tomography scanner was successfully developed because of the collaboration between an imaginative engineer, Godfrey Hounsfield, who created the machine, and a brilliant neuroradiologist, James Ambrose, who demonstrated its wide clinical significance. CONCLUSION: The computed tomography scanner represents one of the most important contributions to neurosurgical practice in the past 100 years, and its development is a remarkable story of scientific endeavor.

Endurance of aneurysm clips: mechanical endurance of Yasargil and Spetzler titanium aneurysm clips.

OBJECTIVE: To determine whether repeated use weakens titanium aneurysm clips, making them unsafe for clinical use. METHODS: Nine Yasargil (titanium alloy) and five Spetzler (pure titanium) clips were subjected to clinically relevant maneuvers, and the effects on the closing force were assessed. Clips were considered unsafe if 1) the blades crossed, 2) the clips failed to close completely, or 3) the blood pressure could open them. RESULTS: Yasargil and Spetzler clips significantly (P < 0.01 for both) weakened, by 18.9% and 26.1%, respectively, after 10 minutes of sustained maximal opening. After 100 open-close cycles, Spetzler clips showed no change in closing force, but the closing force of Yasargil clips decreased significantly (P < 0.01), by a further 12.0%. CONCLUSION: Repeated use weakens Spetzler and Yasargil clips. All Spetzler and all but one Yasargil clips were deemed safe for clinical use at the end of the experiments.